A vehicle lamp can generally switch between a low beam and a high beam. The low beam provides a predetermined illumination for a nearby area and has a light distribution designed not to give glare to an oncoming vehicle or a preceding vehicle. The low beam is mainly used when driving in urban areas. On the other hand, the high beam provides a bright illumination for a front wide area and a distant area and is mainly used when driving at high speed on a road with few oncoming vehicles or preceding vehicles. Therefore, although the high beam gives better visibility to a driver than the low beam, the high beam would give glare to a driver of a preceding vehicle or a pedestrian in front of the vehicle.
In recent years, Adaptive Driving Beam (ADB) technique which dynamically and adaptively controls a light distribution pattern of a high beam based on conditions surrounding the vehicle has been proposed. The ADB technique reduces glare to a vehicle or a pedestrian by detecting presence of a preceding vehicle, an oncoming vehicle or a pedestrian in front of the vehicle and reducing light of an area corresponding to the detected vehicle or pedestrian.
As a method for realizing an ADB function, a shutter method for controlling an actuator, a rotary method, an LED array method, or the like have been proposed. In the shutter method or the rotary method, a width of a turning-off region (light blocking region) can be continuously changed, but the number of turning-off regions is limited to one. In the LED array method, a plurality of turning-off regions can be set, but since the width of each of the turning-off regions is restricted by an illumination width of a LED chip, the width of the turning-off regions would be discrete.
The applicant of the present application has proposed a scanning method as an ADB method capable of solving these problems (refer to Patent Document 2). In the scanning method, light is made incident on a rotating reflector (blade), the incident light is reflected at an angle corresponding to a rotational position of the reflector, and the reflected light is scanned in front of a vehicle while a desired light distribution pattern is formed in front of the vehicle by turning on/off a light source or changing a light amount according to the rotational position of the reflector.